ObjC: Split out NV12 texture uploading into separate class

webrtc/sdk/objc/Framework/Classes/RTCNV12TextureCache.h

Index: webrtc/sdk/objc/Framework/Classes/RTCNV12TextureCache.h
diff --git a/webrtc/sdk/objc/Framework/Classes/RTCNV12TextureCache.h b/webrtc/sdk/objc/Framework/Classes/RTCNV12TextureCache.h
new file mode 100644
index 0000000000000000000000000000000000000000..0aa7a5718177b01678622b550cc001fdb290bd31
--- /dev/null
+++ b/webrtc/sdk/objc/Framework/Classes/RTCNV12TextureCache.h
@@ -0,0 +1,30 @@
+/*
+ *  Copyright 2017 The WebRTC project authors. All Rights Reserved.
+ *
+ *  Use of this source code is governed by a BSD-style license
+ *  that can be found in the LICENSE file in the root of the source
+ *  tree. An additional intellectual property rights grant can be found
+ *  in the file PATENTS.  All contributing project authors may
+ *  be found in the AUTHORS file in the root of the source tree.
+ */
+
+#import <GLKit/GLKit.h>
+
+@class RTCVideoFrame;
+
+NS_ASSUME_NONNULL_BEGIN
+
+@interface RTCNV12TextureCache : NSObject
+
+@property(nonatomic, readonly) GLuint yTexture;
+@property(nonatomic, readonly) GLuint uvTexture;
+
+- (nullable instancetype)initWithContext:(EAGLContext *)context;
+
+- (BOOL)uploadFrameToTextures:(RTCVideoFrame *)frame;
+
+- (void)releaseTextures;
+
+@end
+
+NS_ASSUME_NONNULL_END